本文介绍了如何从MySQL表中选择列为NULL的数据的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我希望下面的代码向我显示表中交换列为null但结果集显示0行的所有记录.知道为什么吗?
I expect the following code to show me all the records in the table where the exchange column is null but the result set show 0 rows. Any idea why?
SELECT * FROM pubco WHERE exchange IS NULL;推荐答案
也许您已将''解释为NULL,但这并不相同,请尝试
maybe you have interpreted '' as NULL which is not the same, but try this
SELECT * FROM pubco WHERE exchange IS NULL OR exchange = ''但是如果仍然没有获得值,也许它上面有空格,所以您应该TRIM它,
but if still not getting the value, maybe it has spaces on it, so you should TRIM it,
SELECT * FROM pubco WHERE exchange IS NULL OR TRIM(exchange) = ''更多推荐
如何从MySQL表中选择列为NULL的数据
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